This invention relates generally to apparatus for inflating devices, in particular to apparatus for inflating aircraft emergency evacuation slides and rafts.
Aircraft emergency evacuation slides, emergency life rafts and similar devices are typically stored in a packed configuration occupying as little space as possible for long periods of time. When called upon for use, these inflatable devices are typically inflated to a relatively low pressure, on the order of 2-3 psig for conventional aircraft evacuation slides up to approximately 7-8 psig for advanced high pressure lightweight evacuation slides. The requirement that the inflatable device in its packed condition occupy a minimum volume dictates that the inflation source comprise a volume of gas stored in a high pressure container, a pyrotechnic gas generator, or a hybrid inflator comprising a pyrotechnic gas generator in combination with a quantity of gas stored at high pressure.
Because the aforementioned high pressure inflation sources exhaust a volume of gas at a pressure substantially higher than the inflation pressure of the inflatable device, it is common to use an aspirator to draw atmospheric air into the inflatable device during inflation to augment the high pressure gas flowing into the inflatable device. In the operation of an aspirator, one or more nozzles act as gas injectors, injecting a jet stream of gas at high velocity into the inlet end of an aspirator barrel. The flow of air entering the aspirator barrel reduces the pressure at the inlet end to below atmospheric pressure. Atmospheric air, therefore, enters the aspirator body to be entrained with the jet stream entering the aspirator barrel. The outlet of the aspirator barrel communicates with the interior volume of the inflatable device so that jet stream and the entrained air collectively make up the volume of gas filling the inflatable device.
Because the aspirator barrel must be capable of operating at sub-atmospheric pressure without collapsing, aspirators are conventionally equipped with rigid aspirator barrels. Although a rigid aspirator barrel adequately performs the function of entraining atmospheric air into the jet stream produced by the injector nozzle(s) a rigid aspirator barrel adds significant weight and storage volume to the inflatable device. U.S. Pat. No. 5,002,465 to Lagen et al. and U.S. Pat. No. 6,071,084 to Wass et al. suggest aspirators having telescoping aspirator barrels. Although a telescoping aspirator barrel reduces the storage volume of the aspirator to some extent, a telescoping aspirator barrel typically collapses by only about 20% or less and, therefore, 80% or more of the length of the rigid aspirator barrel remains to be stored in the limited volume for storage of the inflatable device.